Avigon et Lyon, Seguin et chez l’auteur, 1777. 12mo, full vellum. 207 pp. An early guide to rare-book collecting; a priced-catalog of books sold by Jean-François de Los Rios, with annotations. de Los Rios (1727-1820) was a noted bookseller in Lyon, famously taking advantage of the dispersion of Jesuit libraries after the order was expelled from France in 1764. The Bibliographie instructive was one of his early works, published after more than 17 years as a bookseller in Lyon. The bilbiografía is organized as a directory with 639 entries briefly discussed and 190 references in the included supplement. The entries are organized thematically. Los-Rios also offered an "index auctorum" to facilitate locating the names and titles. A scarce early work on the trade. Covers soiled and slightly cocked; edges discolored; corners bumped. Contemporary inked inscription inside front cover. Interior clean and tight with some light toning but no foxing. $500